<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      width: 1000px;
      height: 300px;
      background-color: pink;
      margin: 0 auto;
    }
  </style>
</head>

<body>
  <!-- 版心居中 -->
  <!-- 版心：网页的有效内容 -->
  <div>版心</div>

</body>

</html>